For a magnetic suspension system, coupling between every two degrees of freedom is usually neglected, a decentralized control method is adopted to implement control over five degrees of freedom, and each degree of freedom is independently controlled. However, as a high-speed rotating object, a shaft of the magnetic suspension system may inevitably whirl, whirling includes cylindrical whirling and conical whirling, and conical whirling is vigorous at high speed. Cylindrical whirling is similar to translation, front and rear ends of the slender shaft of the magnetic suspension system are displaced under the same amplitude and phase during cylindrical whirling, and the front and rear ends are usually displaced in opposite directions during conical whirling. During practical work, a displacement signal detected by a sensor is displacement generated by synthesis of the two kinds of movement. Under the condition that each degree of freedom is independently controlled, whirling may not be controlled, and vigorous whirling is very likely to cause instability of the magnetic suspension system during high-speed rotation, so that it is absolutely necessary to effectively control whirling.
At present, the following method is usually adopted to suppress whirling: some decoupling control algorithms such as cross feedback control are added on the basis of decentralized control, or a centralized control method is adopted. These methods have shortcomings of algorithm complexity, heavy calculation and difficulty in implementation in a Digital Signal Processor (DSP).
For the problem of difficulty in suppression of whirling of a shaft during high-speed rotation of a magnetic suspension system in a conventional art, there is yet no effective solution.